In a notebook personal computer, music terminal, and information terminal, while miniaturization and thinning advances, multi-functionalization progresses at the same time owing to improvement in operation throughput or the like, and data volume to process is also increasing. In such apparatus, in addition to internal memories, such as a semiconductor memory, it is desired to mount a relatively cheap and large-capacity hard disk storage apparatus.
However, a magnetic storage apparatus like a hard disk apparatus is vulnerable to external force structurally such as a fall, vibration, or shock. In consideration of protecting the magnetic storage apparatus from mechanical factors, such as vibration and shock, it is necessary to roughly divide the state between operation time and non-operation time of the magnetic storage apparatus before consideration. The magnetic storage apparatus here generally has the swing arm head structure driven by a voice coil motor (VCM). Since this structure is suitable for moving a head at high speed, it is possible to respond to higher speed and larger capacity. The operation time indicates the state in which the head is positioned over a disc, and performing the tasks such as writing to or reading from the magnetic disk. The non-operation time indicates that at other time than the operation time, the head is evacuated from the disk and the rotation of the disk is stopped in some cases.
At the operation time, the head is over the magnetic disk and slightly floats by air pressure, however when the head contacts the magnetic disk by vibration or shock, there is a possibility of giving a scratch. For this reason, if excessive acceleration is applied to the magnetic storage apparatus, the head may be at the position to evacuate from the magnetic disk.
At the non-operation time, the head is evacuated from the disk and the head will not directly scratch the disk. However the head is held only by a VCM magnet and induced electromotive force of the coil, thus if external force of a certain fixed value or more is applied, the head mores over the disk, and there is a possibility of scratching the disk.
In order to prevent the head from contacting the magnetic disk by a vibration or shock, there are many methods suggested to attach a shock absorbing material typified by a rubber material and gel material in a gap between the magnetic storage apparatus and the housing to hold the magnetic storage apparatus.
Patent documents 1 and 2 disclose to include an elastic shock absorbing body which absorbs shock energy by elastic deformation, and the plastic shock absorbing body which absorbs shock energy by plastic deformation, between a disk drive and a case in order to protect the built-in device from shock. A shock less than or equal to a certain acceptable value is absorbed by deformation of the elastic shock absorbing body, and a shock more than or equal to the certain acceptable value is absorbed by deformation of the plastic shock absorbing body.
Patent documents 3 and 4 disclose to supply a plurality of anti-vibration rubber between a mounting frame of the head disk assembly, have a different strength for at least one of the anti-vibration rubber from the other anti-vibration rubber, so as to stabilize the hold state of the head disk assembly.
[Patent Document 1]
    Japanese Unexamined Patent Application Publication No. 2002-358140[Patent Document 2]    Japanese Unexamined Patent Application Publication No. 2003-242764[Patent Document 3]    Japanese Unexamined Patent Application Publication No. 03-104079[Patent Document 4]    Japanese Unexamined Patent Application Publication No. 01-46284